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| United States Patent |
6,159,302
|
|
Xavier
, et al.
|
December 12, 2000
|
Neutral phosphate pre-coagulant composition for clarification in white
sugar production
Abstract
Methods and compositions for clarifying sugar are disclosed. Compositions
of a condensation polymer of a dihaloalkyl compound and a dialkylamine
compound and a phosphate compound are effective at clarifying the sugar
syrup during its production as well as reducing the total amount of
phosphate used.
| Inventors:
|
Xavier; Carlos Roberto (Araraquara, BR);
Luiz; Claudio Candido (Cotia, BR);
Fernandes; Luiz Antonio (Sao Paulo, BR)
|
| Assignee:
|
BetzDearborn Inc. (Trevose, PA)
|
| Appl. No.:
|
231384 |
| Filed:
|
January 13, 1999 |
| Current U.S. Class: |
127/57; 210/728; 252/181 |
| Intern'l Class: |
C13D 003/16 |
| Field of Search: |
127/57
210/728
252/181
|
References Cited
U.S. Patent Documents
| 3418165 | Dec., 1968 | Rabe.
| |
| 3476597 | Nov., 1969 | Lippe et al.
| |
| 3808050 | Apr., 1974 | Paley.
| |
| 3909287 | Sep., 1975 | Rundell et al.
| |
| 3926662 | Dec., 1975 | Rundell et al.
| |
| 3994743 | Nov., 1976 | Paley.
| |
| 4039348 | Aug., 1977 | Hunwick.
| |
| 4081288 | Mar., 1978 | Torres.
| |
| 4492601 | Jan., 1985 | Nakasone et al.
| |
| 4499112 | Feb., 1985 | Miller et al.
| |
| 4523959 | Jun., 1985 | Exertier.
| |
| 4655934 | Apr., 1987 | Rose et al. | 210/728.
|
| 4765867 | Aug., 1988 | Dreisbach et al.
| |
| 5110363 | May., 1992 | Clarke et al.
| |
| 5554227 | Sep., 1996 | Kwok et al.
| |
| 5891254 | Apr., 1999 | Coville et al. | 127/48.
|
Other References
1998:761841 CAPLUS, Gibson et al, "Modified magnesium hydroxide slurry . .
. ", Nov. 5, 1998.
1987:578508 CAPLUS, Zakharov et al, "Clarifying of saturation juice . . .
", Oct. 8, 1984.
1992:492558 CAPLUS, Perez et al, "Effect of chemical reagents added . . .
", 1990.
|
Primary Examiner: Brunsman; David
Attorney, Agent or Firm: Greenblum & Bernstein, P.L.C.
Claims
Having thus described the invention, what we claim is:
1. A method for clarifying sugar syrup during production of sugar
comprising adding to said syrup an effective clarifying amount of a
composition of a condensation polymer of a dihaloalkyl compound and a
dialkylamine compound and a phosphate compound, the phosphate compound
comprising at least one water soluble compound which does not
substantially decrease the pH of the sugar syrup.
2. The method as claimed in claim 1 wherein said dialkylamine compound
comprises at least one of dimethylamine, diethylamine, dipropylamine,
dibutylamine, and dipentylamine.
3. The method as claimed in claim 1 wherein said dihaloalkyl is
epichlorohydrin.
4. The method as claimed in claim 1 wherein said condensation polymer is
derived from the polymerization of epichlorohydrin and dimethylamine.
5. The method as claimed in claim 4 wherein said condensation polymer has a
molecular weight ranging from about 8000 to about 14,000.
6. The method as claimed in claim 1 wherein said phosphate compound
comprises at least one of halogen salts of phosphorous; tripolyphosphates;
pyrophosphates; hexametaphosphates; and trisodium phosphates.
7. The method as claimed in claim 6 wherein said phosphate compound is
sodium tripolyphosphate.
8. The method as claimed in claim 7 wherein said sodium tripolyphosphate is
food grade.
9. The method as claimed in claim 1 wherein said sugar syrup is in a
flotation or clarification system of a sugar making system.
10. The method as claimed in claim 1 wherein said sugar syrup is derived
from cane sugar.
11. The method as claimed in claim 1 wherein said composition is added to
said sugar syrup in an amount ranging from about 50 parts to about 250
parts per million parts sugar syrup.
12. The method as claimed in claim 1 wherein the weight ratio of
condensation polymer to phosphate compound ranges from about 2 to about 1.
13. A composition useful in clarifying sugar syrup comprising a
condensation polymer of a dihaloalkyl compound and a dialkylamine compound
and a phosphate compound, said phosphate compound comprising at least one
water soluble compound which does not substantially decrease the pH of the
sugar syrup.
14. The composition as claimed in claim 13 wherein said dialkylamine
compound comprises at least one of dimethylamine, diethylamine,
dipropylamine, dibutylamine, and dipentylamine.
15. The composition as claimed in claim 14 wherein said dihaloalkyl is
epichlorohydrin.
16. The composition as claimed in claim 13 wherein said condensation
polymer is derived from the polymerization of epichlorohydrin and
dimethylamine.
17. The composition as claimed in claim 16 wherein said condensation
polymer has a molecular weight ranging from about 8,000 to about 14,000.
18. The composition as claimed in claim 13 wherein said phosphate compound
comprises at least one of halogen salts of phosphorous; tripolyphosphates;
pyrophosphates; hexametaphosphates; and trisodium phosphates.
19. The composition as claimed in claim 18 wherein said phosphate compound
is sodium tripolyphosphate.
20. The composition as claimed in claim 19 wherein said sodium
tripolyphosphate is food grade.
Description
FIELD OF THE INVENTION
The present invention provides for methods and compositions for clarifying
sugar solutions while lowering the amount of phosphate-based compound
employed.
BACKGROUND OF THE INVENTION
After sugar is extracted from prepared cane, the resultant mixed juice
(water, sucrose and other impurities) needs to be clarified. In the
production of white sugar, this clarification is important as the better
the clarification of the sugar juice, the better (i.e., more white) the
final sugar will be.
The coagulation of the impurities in this stream is very important in
achieving a good end product. After the clarification stage, the
evaporation stage takes place. Any impurities present causing color
problems in the liquid also get concentrated in the same proportion as the
sugar juice does. Color levels of up to 6,000 to 10,000 ICUMSA color units
are often obtained in this stage.
As such, a majority of sugar mills will clarify the sugar syrup after the
evaporation stage. This process is typically accomplished by
pre-coagulating the sugar syrup and passing it through a flotation system.
If phosphoric acid is used as the phosphate source in the pre-coagulation
step, lime or calcium sacharate is used to neutralize this and maintain
the pH of the sugar syrup in the neutral range to avoid sugar inversion.
This neutralization step can be a complicated operation due to solids level
content. Sugar syrup can have 60 to 70% solids content and these can
deposit over the pH meter's electrodes reducing its sensitivity and
causing pH variations. These variations in pH can cause the color of the
clarified syrup to be higher than before the clarification step. This
substantially compromises the quality of the final sugar.
Additional complications arise due to the sugar syrup's high concentration.
This high concentration causes lime dissolution to be slow and the pH
adjustment will take more time to happen. This slow response will cause an
overfeed of lime or calcium sacharate which in turn will cause a pH
increase to levels other than the correct one and will result in high
color and high ash content in the final sugar product.
Further difficulties can arise when this syrup is then passed to the
evaporator systems. These systems are usually in a series of vessels each
of which has a greater vacuum than the previous one. This process will
concentrate the sugar juice even further. The use of phosphoric acid and
other phosphate compounds in the clarification stage can cause scaling
problems in the evaporation stage. The high phosphate concentration, when
concentrated even more in the evaporation stage can crystallize and
precipitate out causing deposition in the evaporative stage.
The present inventors have discovered a novel precoagulant composition that
reduces the amount of phosphate employed and reduces the amount of scale
formed in the evaporation stage of the sugar making process.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for an improved process for clarifying sugar
syrup during the production of sugar. The method comprises adding to the
sugar syrup during precoagulation an effective amount of a composition
comprising a condensation polymer and a phosphate compound.
The condensation polymer is derived from the condensation polymerization of
epichlorohydrin or a dihalo alkyl compound with a dialkylamine wherein the
alkyl groups of the dialkylamine have from 1 to about 5 carbon atoms.
Exemplary dialkylamines include dimethylamine, diethylamine,
dipropylamine, dibutylamine, and dipentylamine. Preferably, the
dialkylamine is dimethylamine or diethylamine. A preferred embodiment of
this polymer may be derived from the condensation polymerization of
epichlorohydrin with dimethylamine, with a molecular weight from about
8,000 to about 14,000.
Representative phosphate compounds include but are not limited to the
halogen salts such as phosphorous trichloride; tripolyphosphates,
pyrophosphates, hexametaphosphates, and trisodium phosphates. Any
phosphate salt that is water soluble and will not substantially decrease
the pH of the sugar syrup is expected to be within the purview of this
invention. Preferably, the phosphate based compound is food grade sodium
tripolyphosphate such as those commercially available from Monsanto as
NUTRIPHOS 0-88 and Albright and Wilson as ALBRIPHOS 50F.
The inventive method takes place in the flotation or clarification system
of the sugar making system. The sugar syrup is passed to the flotation
system where the sugar syrup is coagulated or pre-coagulated prior to the
syrup being passed to the crystallization phase of the white sugar
production process.
The sugar syrup can be defined as a colloidal suspension composed of
different types and sizes of particles. Table A illustrates the general
composition of this syrup according to particle diameter.
TABLE A
______________________________________
Diameter Weight
Dispersion (.mu.) (%) Types
______________________________________
Rude D > 1 2-5 Small baggass particles,
sand
Colloidals 0.001 < D < 1 0.05-0.3 Waxes, greases, proteins,
gums, colorants, dextranes
Moleculars D < 0.001 8-21 Sugars: sucrose, glucose,
and Ionics fructose, manose
Mineral salts: K, Ca, Mg and
Na sulfates, chlorides,
silicates and phosphates
Organic acids: aconitic,
oxalic, malic, etc.
______________________________________
The coagulation of these impurities is important in achieving the final
product of finished white sugar. According to Stoke's Law, the tendency of
particles to coagulate is inversely proportional to the square of its
diameter. Since 8 to 21% by weight of the sugar syrup juice is composed of
particles smaller than 0.001 micron, the sugar syrup juice coagulation
process does not follow Stoke's Law, but is driven by Zeta potential. Zeta
potential is the electric charge acquired by a particle in a liquid
suspension. The closer to zero this potential is, the better the
coagulation is going to be. Table B illustrates stability characteristics
versus Zeta potential.
TABLE B
______________________________________
Stability Characteristics
Zeta Potential (mV)
______________________________________
Maximum agglomeration and precipitation
+3 to 0
Excellent agglomeration and precipitation -1 to -4
Weak agglomeration and precipitation -5 to -10
Very weak agglomeration -11 to -20
Weak stability (only some agglomerates) -21 to -30
Moderate stability (no agglomerates) -31 to -40
Good stability -41 to -50
Very good stability -51 to -60
Excellent stability -61 to -80
Maximum stability -81 to -100
______________________________________
For purposes of the present invention, the phrase "effective clarifying
amount" is defined as that amount of condensation polymer and phosphate
compound which will clarify the sugar syrup. Preferably, this ranges from
about 50 parts of the composition to about 250 parts per million parts of
sugar syrup.
The weight ratio of condensation polymer to phosphate compound is generally
in the range of about 10 to about 5 with a weight ratio of about 2 to
about 1 preferred.
The inventive composition may be added to the sugar syrup as a combination
or as individual ingredients. Preferably the composition is added to the
sugar syrup prior to its arrival in the flotation system, but may also be
added directly to the syrup in the flotation system.
The invention will now be described with reference to a number of specific
examples, which should not be considered as limiting the scope of the
claimed invention.
EXAMPLES
Testing was performed to measure lime reduction using neutral phosphate
sources in comparison to phosphoric acid. 200 ml of sugar syrup was
transferred to a 500 ml beaker. This syrup has a density of 1.085
g/cm.sup.3, a brix of 21.5, an original ICUMSA IV number of 9182 and a pH
of 5.0.
The temperature of the sucrotest device was first adjusted to 85.degree. C.
and mixed strongly for about 1 minute.
The syrup was then transferred to the sucrotest graduated tube while the
anionic polymer solution was simultaneously added. The tube was then
capped and the agitation and air injection was begun at 65 to 70 rpm for 1
minute.
The size of the formed flakes and flotation velocity was observed. After 20
minutes, a sample was taken and diluted to 10.degree. brix. This sample
was filtered through a 47 .mu. Millipore membrane under vacuum. The
absorbance and the transmittance of the filtered sample were measured at
420 nm wave length.
The ICUMSA IV color was calculated using the formula:
##EQU1##
where: Density=density of filtered diluted syrup sample Brix=brix of the
filtered diluted syrup sample
Cuvet width=1.0 cm
The results of this testing are presented in Table I. The higher the
percent transmittance, the better the clarification of the syrup.
TABLE I
______________________________________
Clarification of Sugar Syrup
pH = 7 at 100.degree. C.
No SO.sub.2 oxidant
Pre- Anionic
Lime Coagulant Coagulant ABS Trans ICUMSA IV
Test (mL/L) (ppm) (ppm) (420 nm) (%) Color
______________________________________
1 5.5 -- 2.0 0.6070 24.7 5848
2 4.2 A (50) 2.0 0.5310 30.6 5116
3 4.0 B (250) 2.0 0.4535 35.8 4369
______________________________________
Precoagulant A is sodium tripolyphosphate
Precoagulant B is 20% dimethylamineepichlorohydrin copolymer and 10%
sodium tripolyphosphate, by weight, in water
These results demonstrate that the inventive composition is more effective
than the use of just a phosphate compound at clarifying the sugar syrup
while reducing the overall amount of phosphate containing compound
employed.
Further testing was performed in the sucrotest device. These results are
presented in Table II.
TABLE II
______________________________________
Clarification of Sugar Syrup
pH = 7 at 100.degree. C.
No SO.sub.2 Oxidant
2.0 ppm of Anionic Polymer
Pre-
Lime Coagulant ABS Trans ICUMSA IV
Test (mL/L) (ppm) (420 nm) (%) Color
______________________________________
1 5.5 -- 0.6070 24.7 5848
2 5.0 A (50) 0.5795 28.4 5583
3 5.0 B (50) 0.5130 31.5 4942
4 5.0 A (100) 0.5415 29.7 5217
5 4.3 B (100) 0.5135 31.3 4947
6 4.0 A (150) 0.5230 30.2 5039
7 3.8 B (150) 0.4530 35.5 4364
8 3.8 A (200) 0.5460 30.2 5260
9 3.5 B (200) 0.4040 39.6 3892
10 3.3 A (250) 0.4650 34.5 4480
11 3.3 B (250) 0.3840 41.1 3699
______________________________________
A is sodium tripolyphosphate
B is 20% dimethylamineepichlorohydrin copolymer and 10% sodium
tripolyphosphate, by weight, in water
As seen in Table II, the inventive composition was more effective than the
phosphate containing compound at producing a more clarified sugar solution
from a range of 50 to 250 ppm active.
While this invention has been described with respect to particular
embodiments thereof, it is apparent that numerous other forms and
modifications of this invention will be obvious to those skilled in the
art. The appended claims and this invention generally should be construed
to cover all such obvious forms and modifications which are within the
true spirit and scope of the present invention.
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